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src/audio/audio_downloader.h

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+#pragma once
+
+#include <atomic>
+#include <chrono>
+#include <condition_variable>
+#include <mutex>
+#include <string>
+#include <thread>
+#include <vector>
+
+namespace radiantwave::db {
+class DatabaseManager;
+}
+
+namespace radiantwave::audio {
+
+// One entry from the audio checksums manifest.
+//
+// Supported line formats (in priority order):
+//   <filename> '<display name>' <hz> <md5>   // current
+//   <md5>  <filename>                        // legacy fallback
+//
+// hz is the actual frequency value of the track (e.g. 396), written by hand
+// or by a script that has no access to the frequency-id table; 0 means
+// "none / unset". The manifest author may also write the frequency id (or any
+// unrecognized number): only values that resolve to a known frequency are
+// honored, anything else falls back to the Hz parsed from the filename, so
+// the file's own name is always the safety net.
+struct AudioManifestEntry {
+    std::string filename;
+    std::string display_name;
+    int solfeggio_frequency_hz = 0;
+    std::string md5;
+};
+
+// Downloads audio assets from files.radiantwavetech.com in the background
+// and keeps the database's audio_files table in sync with what is actually
+// on disk.
+//
+// Fetches checksums.md5, compares each entry against the local file's MD5,
+// and re-downloads anything that is missing or whose checksum differs.
+// Files present on disk but absent from the manifest are deleted, and the
+// audio_files table is reconciled on every pass (and after each individual
+// download) so the settings audio list reflects live progress: a file that
+// just finished downloading appears in the list immediately, and files not
+// yet downloaded are not listed. The worker runs a persistent loop: if
+// there is no internet at startup the status shows "Waiting for internet..."
+// and a download starts automatically once connectivity returns. When all
+// files verify it keeps re-checking the manifest periodically so changed
+// checksums are picked up while running.
+class AudioDownloader {
+public:
+    AudioDownloader() = default;
+    ~AudioDownloader();
+
+    AudioDownloader(const AudioDownloader&) = delete;
+    AudioDownloader& operator=(const AudioDownloader&) = delete;
+
+    // Spawns the background thread. Safe to call repeatedly; only one worker
+    // runs at a time. The manifest is reconciled against `db` on every pass.
+    void start(db::DatabaseManager& db);
+
+    // Signals the worker to stop and joins the thread.
+    void shutdown();
+
+    // Returns the current human-readable status for display (e.g. footer).
+    std::string statusString() const;
+
+    static constexpr const char* AUDIO_BASE_URL = "https://files.radiantwavetech.com/audio/";
+    static constexpr const char* MANIFEST_FILENAME = "checksums.md5";
+
+private:
+    void run();
+    bool fetchManifest(std::vector<AudioManifestEntry>& out);
+    bool downloadAndVerify(const std::string& filename, const std::string& expectedMd5);
+
+    void setStatus(const std::string& msg);
+    void wait(std::chrono::seconds seconds);
+
+    mutable std::mutex mutex_;
+    std::condition_variable cv_;
+    std::thread worker_;
+    std::atomic<bool> stop_{false};
+    std::string status_;
+    db::DatabaseManager* db_ = nullptr;
+};
+
+// Parses checksums.md5 manifest text into entries. Blank lines and lines
+// starting with '#' are ignored. Lines that don't match a known format are
+// skipped. Returns false if no valid entries were found.
+bool parseManifest(const std::string& text, std::vector<AudioManifestEntry>& out);
+
+// Maps a frequency value in Hz to its internal solfeggio frequency id using
+// the same table the color palettes are seeded from (174/285->1, 396->2,
+// 417->3, 432->4, 528->5, 639->6, 741->7, 852->8, 963->9). Returns 0 for
+// frequencies with no id (binaurals, AlphaWaves, OriginalAudio, ...).
+int frequencyIdForHz(int hz);
+
+// Parses the leading frequency value out of an audio filename like
+// "396Hz.wav" -> 396. Requires the digits to be followed by "Hz"
+// (case-insensitive); returns 0 when the name has no frequency (e.g.
+// "AlphaWaves.wav", "OriginalAudio.wav").
+int hzFromFilename(const std::string& filename);
+
+// Computes the lowercase MD5 hex of a file, or an empty string on failure.
+std::string computeFileMd5(const std::string& path);
+
+} // namespace radiantwave::audio